Obviously banks require you to have some skin in the game but ideally maximum returns will be achieved with as close to 100% financing as possible.A income property that can not produce positive cash flow with 100% financing will always require that the investor buy their cash flow with their own money.

Eg... if you qualify for the secondary market grab 10 props  ( up to 40 units as you are able to buy up to a 4 unit and still qualify for secondary market funding ) where you can lock in up to 30 year money.

They will understand and most likely be on board.

No skin in the game.

Therefore, you can give your father his money, in full, and not have any downpayment, and be in a 30 year fixed rate (assuming you and property qualify). 

If they have skin in the game, like you do, then you can feel comfortable.  

The FHA's goal is to put those who wouldn't otherwise qualify for a mortgage into their own home, and it is benefit enough that they extend that assistance up to 4 units.

I have some really qualified potentials and I'm curious to know if I have that in back pocket to take away the last month and they can just pay it during lease months.

Usually it's easier to qualify for a loan than it is to amass a downpayment so you're a step a head in that respect. 

I've thought about house-hacking, but there's no way i'd qualify for a mortgage (i only make about $20k/year).